1 Field of the Invention
The present invention relates to a pipe spiral bundle for a heat exchanger, having a number of plane pipe spirals of the same shape which have been arranged in parallel on the same central axis, the loops each single spiral lying inside the other, and spaced at a distance from each other, and all the spirals being connected, by one end of the same name, to a mutual branch pipe and by the other end to a mutual collector pipe. The invention also relates to a method for the manufacture of such a pipe spiral bundle.
2 Description of the Prior Art
Such heat exchangers are used, for example, for heating household water and in the heat distribution centers of central heating systems of apartment buildings. The use of heat exchangers is increasing along with the increased use of district heating.
A heat exchanger with a pipe spiral bundle of the type described above has been described in, for example, Swedish Pat. No. 400,368. In this heat exchanger the pipe spiral bundle is placed inside a cylindrical container, the branch and collector pipes protruding from one end of the container. The pipe bundle itself is assembled by fitting copper pipes of predetermined length side by side on a perforated steel plate to form a pipe mat, whereafter the mat is twisted into a spiral. The purpose of the steel plate is to direct the flow of district heating water or steam, which is fed in at the middle of the bundle and out from the mantle surface of the cylinder.
Since such copper pipe is usually delivered in the form of soft pipe on reels, the above, prior known manufacturing method requires that the pipe be first straightened and then re-bent when the pipe lengths have been fitted on a plate with extensions keeping the pipes in place at a distance from each other.